1. Field of Invention
This invention generally relates to a pump for dispensing parenteral fluid medication and more particularly to a pump which is surgically implanted to administer such medications by the induced flow of an internal reservoir over an extended period of time. In such implant devices find usage for the ambulatory patient requiring an extended regimen such as for a chronic condition or for birth control. About half of all ethical pharmaceuticals are consumed for a chronic condition. Such implant devices also find usage for the acute patient in transit where neither an IV gravity bag, nor continuous injections can be used.
2. Description of the Prior Art
Prior art on continuous medication where the reservoir is external to the patient includes
gravity feed, PA0 power-driven pumps, PA0 elastic bladder pumps, PA0 gas pressurized pumps. For an acute patient in transit, gravity IV may be cumbersome, power may be unavailable, or the duration of elastic bladders and gas pressure pumps may be too short. PA0 osmotic powered pumps, PA0 exuding or diffusion controlled polymers, PA0 eroding systems, and PA0 power-driven pumps. Osmotic implant durations are limited to 30 days. Exuding implants have durations of up to five years, but have decreasing sloped delivery curves as shown in the 1992 Physicians' Desk Reference, page 2484. Eroding implants are difficult to develop because the drug, the vehicle, and the binder must all be compatible, and predictably benign when absorbed. Power-driven pump implants are complex and expensive.
Prior art on continuous medication where the reservoir is internal to the patient as an indwelling implant includes